U.S. patent application number 11/571694 was filed with the patent office on 2007-08-09 for multi-lens lenticular system and lighting device for an autostereoscopic display.
This patent application is currently assigned to SEEREAL TECHNOLOGIES GMBH. Invention is credited to Armin Schwerdtner.
Application Number | 20070183033 11/571694 |
Document ID | / |
Family ID | 34965618 |
Filed Date | 2007-08-09 |
United States Patent
Application |
20070183033 |
Kind Code |
A1 |
Schwerdtner; Armin |
August 9, 2007 |
Multi-lens lenticular system and lighting device for an
autostereoscopic display
Abstract
The invention relates to a multi-lens lenticular system and a
lighting device for an autostereoscopic display. Said display
comprises, in the direction of light, an illuminating matrix (7), a
focusing matrix (8), and a transmissive data panel (5). The
illuminating matrix is provided with a plurality of
light-penetrated controllable openings (21). The focusing matrix
(8) focuses the light of said openings (21) in such a way that the
data panel (5) and a preferred visible zone (6) are illuminated in
a directed manner while being composed of a multi-lens lenticular
system (LM) whose lenticles (L) are structured into several
subordinate lenticles (S1, S2, . . . ). The subordinate lenticles
are arranged such that a multiple number of images having an
associated enlarged brightness distribution (V) ranging from (A) to
(C') is created in the visible zone (6) by the light of an opening
(21) while the resulting images of laterally adjoining openings
(21) overlap in the edge regions thereof, thus creating a nearly
homogeneous brightness distribution (V). The homogeneous brightness
visibly increases the quality of the image for the viewer.
Inventors: |
Schwerdtner; Armin;
(Dresden, DE) |
Correspondence
Address: |
SYNNESTVEDT LECHNER & WOODBRIDGE LLP
P O BOX 592
112 NASSAU STREET
PRINCETON
NJ
08542-0592
US
|
Assignee: |
SEEREAL TECHNOLOGIES GMBH
Blasewitzer Strasse 43
Dresden
DE
01307
|
Family ID: |
34965618 |
Appl. No.: |
11/571694 |
Filed: |
February 9, 2005 |
PCT Filed: |
February 9, 2005 |
PCT NO: |
PCT/DE05/00251 |
371 Date: |
January 5, 2007 |
Current U.S.
Class: |
359/463 ;
348/E13.029; 348/E13.031 |
Current CPC
Class: |
H04N 13/32 20180501;
G02B 30/27 20200101; H04N 13/305 20180501 |
Class at
Publication: |
359/463 |
International
Class: |
G02B 27/22 20060101
G02B027/22 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 2004 |
DE |
10 2004 040 086.5 |
Jul 9, 2004 |
DE |
10 2004 034 782.4 |
Claims
1. Multi-lens lenticular array, particularly for autostereoscopic
displays, with a plurality of lenticles (L) bordering each other
and arranged in parallel, whereby to said lenticles (L) a central
axis (m) which divides the aperture of the lenticle (L) is
assigned, characterized in that each lenticle (L) is structured as
several connected sublenticles (S1, S2, . . . ), whereby all
sublenticles (S1, S2, . . . ) together cover the aperture of the
lenticle (L), and one or several sublenticles (S1, S2, . . . ) are
arranged offset in the axial direction of the central axis (m) of
the lenticle (L) and/or in a lateral direction of the central axis
(m) of the lenticle (L).
2. Multi-lens lenticular array of claim 1 characterized in that the
sublenticles (S1, S2, . . . ) are described by convex spherical
lens segments.
3. Multi-lens lenticular array of claim 1 characterized in that one
or several sublenticles (S1, S2, . . . ) are aligned such that the
optical axis thereof in each case is inclined to the central axis
(m) of the lenticle (L).
4. Multi-lens lenticular array of claim 3 characterized in that
neighboring lenticles (L) have a coherent transition at the
adjacent sublenticles (S1, S2) with a common line of intersection
(s).
5. Multi-lens lenticular array of claim 4 characterized in that
neighboring lenticles (L) have a coherent transition, without an
edge, at the adjacent sublenticles (S1, S2) with a tangential plane
in common
6. Multi-lens lenticular array of claim 1 characterized in that
neighboring lenticles (L) have a discontinuous transition at the
adjacent sublenticles (S1, S2).
7. Multi-lens lenticular array of claim 1 characterized in that
neighboring sublenticles (S1, S2) of a lenticle (L) have a coherent
transition with or without an edge.
8. Multi-lens lenticular array of claim 1 characterized in that in
a lenticle (L) several sublenticles (S1, S2, . . . ) are arranged
symmetrically around a sublenticle which is centered on the central
axis (m) of the lenticle (L).
9. Multi-lens lenticular array of claim 1 characterized in that in
a lenticle (L) all sublenticles (S1, S2, . . . ) are arranged
symmetrically around the central axis (m) of the lenticle (L)
without a sublenticle being arranged centrally.
10. Multi-lens lenticular array of claim 1 characterized in that
the sublenticles (S1, S2, . . . ) of the lenticle (L) have
different radii of curvature (R1, R2, . . . ) and/or centers (M1,
M2, . . . ).
11. Multi-lens lenticular array of claim 1 characterized in that
the sublenticles (S1, S2, . . . ) of a lenticle (L) have equal
aperture sizes.
12. Multi-lens lenticular array of claim 1 characterized in that
one or several sublenticles (S1, S2, . . . ) describe aspheric
and/or asymmetric lens segments.
13. Multi-lens lenticular array of claim 1 characterized in that
the lenticles (L) of the lenticular array have a variable aperture
size.
14. Multi-lens lenticular array of claim 13 characterized in that
the aperture size of the lenticles (L) is a linear function of the
distance of the lenticles from the central axis of the lenticular
array.
15. Multi-lens lenticular array of claim 1 as an illumination
device for an autostereoscopic display, comprising in the direction
of propagation of the light an illumination matrix (7) with a
plurality of matrix-like arranged, controllable openings (21)
illuminated in transmission, or self-luminous light sources (21),
and a focusing matrix (8), consisting of a lenticular array (LM)
with a plurality of adjacent lenticles (L) each of which is aligned
parallel to the columns or lines of the illumination matrix (7),
whereby the matrix (8) of the light from said openings (21) is
focused such that a subsequent transmissive information panel (5)
and a selectable preferred region of visibility (6) are illuminated
in the viewer plane (9) in a directed manner characterized in that
the lenticles (L) of the lenticular array (3) each are divided into
sublenticles (S1, S2, . . . ) and the sublenticles (S1, S2, . . . )
are arranged and aligned such that in the region of visibility (6)
a nearly homogeneous luminance distribution results.
16. Multi-lens lenticular array for an illumination device for an
autostereoscopic display of claim 15 characterized in that the
sublenticles (S1, S2, . . . ) are arranged and aligned such that
the light from an opening (21) in the region of visibility (6)
leads to a multiplied number of images corresponding to the number
of sublenticles (S1, S2, . . . ) which are created with the
luminance distribution (V11 with A,A' to V13 with C,C') thereof,
where the images are laterally shifted and overlapping, and a
resulting broadened luminance distribution (V) in the region (A to
C') is created.
17. Multi-lens lenticular array as an illumination device for an
autostereoscopic display of claim 16 characterized in that the
sublenticles (S1, S2, . . . ) are arranged and aligned such that
the images of laterally neighboring openings (21) originating from
the same lenticle (L) each superimpose in the sloping marginal
regions of said broadened luminance distributions (V) and thus in
the region of visibility (6) a nearly homogeneous luminance
distribution is created.
18. Multi-lens lenticular array as an illumination device for an
autostereoscopic display of claim 17 characterized in that from the
predetermined superimpositions of the luminance distribution (V) as
well as by a defined geometry of the openings (21) the arrangement
and alignment of the sublenticles (S1, S2, . . . ) is defined.
19. Illumination device for an autostereoscopic display of claim 15
characterized in that the focusing matrix (8) consists of a
combination of several multi-lens lenticular arrays (LM).
20. Illumination device for an autostereoscopic display of claim 19
characterized in that one or several multi-lens lenticular arrays
(LM) are combined with further optical means.
Description
FIELD OF THE INVENTION
[0001] The invention relates to an arrangement of lenticular
lenses, particularly for autostereoscopic displays. The invention
relates to lenticular arrays with parallel lenticles in particular
as described by the group of lenticular arrays with cylindrical
lenses.
[0002] The multi-lens lenticular array, for example, is usable in
an illumination device for autostereoscopic displays with a
non-luminous transmissive information panel for the representation
of two-dimensional and three-dimensional information with high
image quality.
[0003] For autostereoscopic displays it is necessary to spatially
separate the right and left views of the image information by means
of an optical projection system. In order to make it possible to
view image information stereoscopically, the left/right image
content provided for the left/right eyes of the viewer must be
supplied to the left/right eyes with as little cross-talk to the
respective other eye as possible.
[0004] The means for meeting this demand is also known as an image
separating device and is realized, for example, by an illumination
matrix and a focusing matrix. These and other major elements of
autostereoscopic displays are realized by lenticular arrays, or
combined with lenticular arrays, respectively, so that lenticular
arrays are very important components.
PRIOR ART
[0005] For autostereoscopic displays, lenticular arrays are often
mentioned in the literature and in a multiplicity of inventions. As
a rule, lenticular arrays are used with single spherical lenticles,
that is lenticles being at least approximately circular.
[0006] U.S. Pat. No. 1,922,932, of 1930, describes a transparent
material that is applied to a window pane to produce a "one-way
vision window". The lenses, which are similar to a lenticular
array, should have a width at least equal to the diameter of the
eye pupil in order to be able to be looked through. This
arrangement consists of horizontal concave or convex lenticles and
prisms. Therefore a viewer whose eyes are near to the non-curved
surface can look through the material, whereas the scene behind it
is distorted for a more distant viewer.
[0007] U.S. Pat. No. 3,740,119 A shows lenticular films with the
aim of multiplying the images and targeted focusing in a projection
apparatus, whereby on said films the known spherical or cylindrical
lens shape of the lenticles is reproduced by polygonal curves
symmetrical about the center line. The achieved prism surfaces
bordering each other produce, depending upon the prism angle,
several projections shifted by a distance. Equidistant images can
be produced by equidistant prism angles.
[0008] WO 99/23513 A1 discloses a transparent film as a double
lenticular array that has on either side a lenticular arrangement
the lenses of which have different radii, their optical axes being
laterally shifted with respect to each other in order to focus in a
3D-display such that a greater depth of field is given.
[0009] JP 2002-031854 A discloses an arrangement of convex
lenticular lenses on the front and rear sides of a double
lenticular array for a rear projection display. The lenticular
array, being the second in the direction of transmission, is
configured in the form of three lenses, that is a central lens and
two lenses symmetrical with respect to the central lens, whereby
each sublenticle is aligned with the accompanying subpixel of the
three subpixels RGB in a color display. This arrangement is
intended to produce a parallel exit of the respective rays from
each subpixel. In this way better effectiveness of light
transmission and better color representation should be
achieved.
[0010] DE 19822342 A1 discloses a design of the lenticular array in
which the lenticles are designed to have the same size as the
subpixels, which are arranged in groups each in the form of
prisms.
[0011] In the following, prior art of an illumination device for an
autostereoscopic display with a non-luminous transmissive
information panel will be considered. Such a display comprises an
illumination matrix as the first unit in the direction of
propagation of the light. In this document, the concept of the
illumination matrix is meant to be the generic term for a matrix
with a plurality of controllable light sources or a matrix with a
plurality of controllable openings illuminated in transmission. The
illumination matrix is, as a rule, implemented to be non-luminous
but consists, for example, of a backlight as the light source and a
shutter with a plurality of matrix-like arranged openings for the
control of light transmission.
[0012] In this document, the optical unit arranged between the
shutter and the transmissive information panel is designated as the
focusing matrix. In the following illustration of the
state-of-the-art, reference is made to this nomenclature.
[0013] The focusing matrix focuses the light exiting from the
openings of the shutter such that the subsequent transmissive
information panel and a selectable preferred region of visibility
in the viewer plane are directionally illuminated. Various,
extensive requirements are therefore established for the focusing
matrix, as said matrix has an essential influence on the properties
of the image in the viewer plane. The matrix has significant
responsibility for the image quality perceived by the viewer, such
as the distribution of brightness.
[0014] Aside from other factors, the distribution of the brightness
within the image depends upon whether the discrete light sources
represented by the openings of the shutter can successfully be
transferred into a brightness distribution which is homogeneous
over the viewer plane.
[0015] For autostereoscopic displays a plurality of versions of the
illumination matrix and the focusing matrix are known. As a rule,
lenticular arrays with simple, convex-spherical lenses are used for
the focusing matrix, but a plurality of embodiments of the focusing
matrix are known as described in the following.
[0016] A fundamental embodiment of an autostereoscopic display is
described in WO9423340 A1 or EP0691000 B1, of the applicant.
[0017] Described is an optical system for the two-dimensional and
three-dimensional representation of information using a
transmission display which is divided for each viewer into
accompanying stereo images, at least one point or line light source
being provided, which, when seen from the viewer or viewers
position, is located behind the transmission display, and further a
collimation and a focusing optical system. A prism of a prism mask
and a phase element of a phase mask with random optical
phase-distribution are assigned to each pixel of the transmission
display, whereby the light corresponding to the stereo images is
bent and focused on to the eyes of the viewer or viewers.
[0018] Another embodiment of an autostereoscopic display is
described in DE 10359403 A1 of the applicant. It discloses an
autostereoscopic multi-user display with a sweet-spot unit. The
display consists of an illumination matrix and a projecting matrix
with a field lens; therefore the focusing matrix here consists of
the projecting matrix and a field lens. The projecting matrix has
the function to project the switched-on elements of the
illumination matrix in appropriate directions into the space before
the display so that the subsequent field lens focuses them as
sweet-spots on the eyes of the viewer. The projecting matrix is
designed as a tandem lenticular array including two parallel,
equally directed single lenticular arrays. Another version of the
projecting matrix provides the use of a double lenticular array.
The field lens is configured as a Fresnel lens or as a holographic
optical element.
[0019] EP0788008 B1 and EP0827350 A3 also describe an arrangement
for an autostereoscopic display. In EP 0788088 B 1 the display
comprises a light source for the radiation of light out of a
plurality of openings and an array of optical elements with various
optical functions in the horizontal and vertical directions to
direct the light of the openings through a transmissive
display.
[0020] The array of optical elements--in this case, the focusing
matrix--consists of a row of cylindrical lenses arranged
horizontally next to each other and aligned to be vertical, each of
which consists of a planar surface and a convex surface (a semi
cylinder).
[0021] EP 0827350 A3 discloses an autostereoscopic display. It
consists of a light source for illumination, a planar illuminant,
and a carrier mask with a chessboard-like arrangement of openings
and further a vertical cylindrical lens array--the focusing matrix
in this case--consisting of vertical cylindrical lenses (semi
cylinders) and a transmissive display. Similar to the
last-mentioned document the lens array functions to direct the
light of the openings through the transmissive display.
[0022] EP0881844 B4 describes another arrangement of an
autostereoscopic display; here the focusing matrix comprises a
first lenticular mask with horizontal semi cylinder-shaped
lenticles, a diffuser and another lenticular mask with horizontal
semi cylinder-shaped lenticles.
[0023] EP1045596 A2 discloses another optical system as the
focusing matrix; in this case the matrix consists of an array of
vertically arranged cylindrical lenses followed by, in the
direction of light propagation, an array of horizontally arranged
cylindrical lenses. The lenses of the lens arrays each are aligned
at a distance matching the pattern of the openings of the
shutter.
[0024] JP7234459 describes a lenticular array comprising a
plurality of lenticles located parallel to the stripes of vertical
openings of a shutter. The lenticles of this focusing matrix, the
aperture of which is equal to the stripe distance, are designed to
be semi cylindrical.
[0025] DE 297 10 551 U1 describes an autostereoscopic arrangement
for the three-dimensional representation of information using a
color display. In front of the color display a laterally slidable
prism mask is placed and is provided with one prism wedge per image
column, whereby each prism wedge is equivalent to the width of the
image columns and the prism angle is chosen such that the left
columns of the display are seen by the left eye and the right
columns are seen by the right eye.
[0026] An essential requirement of the illumination matrix and,
particularly, of the focusing matrix is that the information panel
and the preferred region of visibility are illuminated as
homogeneously as possible in the viewer plane; in the
above-mentioned documents this is not realized in a desirable
manner.
[0027] The alignment of the bundles of rays of single lenticles to
form completely illuminated areas in the viewer or projection plane
is not presented or described in great detail in the documents,
although this considerably influences the quality of the visible
image within the projection.
[0028] Considering the separated discrete light sources--due to the
openings of the shutter--with shaded interstices, the bundles of
rays are not sufficiently aligned with respect to each other. In
particular, the images of the interstices produce transitions with
low luminance in the preferred region of visibility, which hence
are perceivable by the viewer as unwanted narrow dark lines--zones
of low luminance. This leads to the disadvantage of a recognizably
worse image quality.
[0029] For a homogeneous illumination of the region of visibility
it is necessary to superimpose the images of the openings in the
region of visibility, that is to blur and/or distort the image of
an opening and the associated ray paths. This superimposition is
not reached, or cannot be reached, to a sufficient extent by the
cylindrical, semi cylindrical, or spherical lenticles in the
above-mentioned solutions.
[0030] To superimpose the paths of rays, an aspheric lenticle, or
even an asymmetric aspheric lenticle, would be required; these
types of lenticles as part of the focusing matrix are not included
in the above-mentioned documents so that recognizably worse image
quality with respect to a homogeneous luminance distribution can
occur.
[0031] Further it is necessary, particularly with autostereoscopic
displays, to avoid, or reduce, all known side effects of the
optical system such as aberrations, moire, coma, and the like,
including pseudoscopic or inhomogeneous luminance distribution. In
addition, it is necessary to create a stereoscopic vision region as
wide and as homogeneous as possible free of cross-talk--the
sweet-spot. With cross-talk, or pseudoscopy, the right eye sees
image portions that are meant for the left eye, and vice versa.
Cross-talking results in pseudoscopic images which differ from the
intended stereoscopic images by inverted depth of field.
[0032] In order to eliminate or at least reduce the above-mentioned
optical side effects, also here an aspheric lenticle, or even an
asymmetric aspheric lenticle would be required.
[0033] These types of lenticles as part of an autostereoscopic
display, however, are not included in the documents mentioned above
as prior art so that a recognizably worse image quality, for
example with respect to a homogeneous luminance distribution, image
separation, and a cross-talk-free sweet-spot region or the like can
occur.
[0034] Aspheric and/or asymmetric lenticles, however, are
disadvantageous in that they are difficult to manufacture and, as a
rule, can be produced only at a very high expense, particularly
when seen from the miniaturization point of view. In order to reach
these goals, often the lens dimension, i.e. the pitch of the
lenticles, is coupled to the pitch of an image matrix. The term
"image matrix" is used here as the generic term for self-luminous
or transmissive displays.
[0035] If only one pixel column of the image matrix, for example,
is allocated to a lenticle of the lenticular array, several serious
problems result as the pixel dimensions of the image matrix
continuously decrease. With further reduction in size of the pixels
as the reference dimension, the danger arises that the bounds of
optical feasibility would be reached, at least with regard to
cost-effective and process-reliable manufacture of the lenticular
arrays.
[0036] Also, if a lenticle contains spherical cylindrical lenses
and is assigned to a few pixel columns only, the limits of a
process-reliable manufacture of the lenticular arrays with this
shape are soon reached. Economic and process-reliable manufacture
generally appears to be problematic. Compared with spherical
lenticles, the production effort further rises for asymmetric
and/or aspheric lenticles.
[0037] While keeping the above-mentioned tasks in mind--reduction
of the optical side effects--a lenticular array should be created
that features the advantageous optical properties of an aspheric
and/or asymmetric lenticle, and which can be simply designed, as
required by manufacture and adjustment, and produced at low cost
and reliably, also under the aspects of miniaturization.
SUMMARY OF THE INVENTION
[0038] A multi-lens lenticular array, particularly for
autostereoscopic displays, consists of a plurality of lenticles
adjacent to each other and arranged in parallel. A central axis,
which divides the aperture of the lenticle, is assigned to each
lenticle.
[0039] The invention is based on an idea to discretely approximate
an individual aspheric and/or asymmetric lenticle by a lenticle
that is structured as a number of simply shaped sublenticles. To
achieve this, the lenticle is divided into a number of individual
sublenticles, which are further defined by their centers and radii
of curvature.
[0040] According to the invention one or several sublenticles are
arranged in the axial direction, i. e. in the direction of the
central axis of the lenticle, and/or in a lateral direction offset
from the central axis of the lenticle. The lateral direction is
defined by the reference vector lying in the plane of the
lenticular array orthogonal to the parallel lenticles.
[0041] In terms of the approximation to an individual aspheric
and/or asymmetric lenticle, the division of the lenticle into
sublenticles and their alignment, namely the location of their
centers and their respective radii of curvature, can be varied. To
achieve this, the sublenticles preferably are described by convex
spherical lens segments.
[0042] A further preferred embodiment provides that a sublenticle
or several sublenticles are aligned such that the optical axis of
each sublenticle is inclined to the central axis of the
lenticle.
[0043] The sublenticles on the margins of the lenticle, for
example, have an inclined optical axis, whereby, in particular,
these sublenticles can be offset in the axial direction of the
central axis of the lenticle.
[0044] The invention is based on the idea that a sublenticle, whose
optical axis is inclined relative to the central axis of the
lenticular array, can be interpreted as an implicit combination of
a spherical lens and a wedge term. Utilizing this idea of the
invention, particularly the above-mentioned preferred embodiment
with the inclined sublenticles, i. e. the inclined wedge terms, can
reduce many disturbing side effects of the optical system.
[0045] Generalizing, said embodiment of the invention can reduce
the effect of light being directed along incorrect paths. For
example, in autostereoscopic displays those bundles of rays that
run through the margin of the lenticle result in aberrations in
which light is bent to a region not visible to the viewer.
[0046] In another embodiment, several sublenticles within a
lenticle are arranged symmetrically around a sublenticle centered
on the central axis of the lenticle. Preferably, the centered
sublenticle is relatively large and covers nearly the entire
aperture of the lenticle, whereby the sublenticles, preferably
inclined, arranged at the margins of the lenticle can serve, for
example, to lessen the side effects of the aberrations.
[0047] In another embodiment, the aperture of the lenticles of the
lenticular array is variable and is, for example, a linear function
of the distance of the lenticle from the central mid-axis of the
lenticular array. Such a functional connection, for example, is
given by the distance of the lenticle from the viewer.
[0048] Further embodiments concern the transition of the
sublenticles within a lenticle or the transition of neighboring
sublenticles. As to details of the definitions and embodiments, see
FIG. 3 which follows.
[0049] Another embodiment of the invention is described by an
illumination device for an autostereoscopic display. Such an
exemplary display consists, in the direction of light propagation,
of an illumination matrix, a focusing matrix, and a subsequent
transmissive information display. In detail, the illumination
matrix includes, given in the direction of light propagation, an
illumination matrix and a focusing matrix. The illumination matrix
consists of a plurality of matrix-like arranged controllable
openings illuminated in transmission, or of self-luminous light
sources. As a rule, the illumination matrix consists of a backlight
as the light source and a shutter with controllable openings for
controlled illumination in transmission. With its intermediate
spaces of lower illumination in transmission, which are caused by
design, the shutter has a plurality of matrix-like arranged
openings.
[0050] The subsequent focusing matrix consists of a lenticular
array with a plurality of lenticles bordering each other which are
each aligned parallel to the columns or lines of the openings of
the shutter.
[0051] The focusing matrix is followed by a transmissive
information panel.
[0052] The matrix focuses the light from the openings in the
shutter such that the information panel and a selectable preferred
region of visibility in the viewer plane are illuminated directly.
p According to the invention the focusing matrix consists of a
multi-lens lenticular array, the lenticles of which each are
divided into sublenticles. According to the invention the
sublenticles are arranged and aligned such that they produce in the
region of visibility a multiple number of images of the openings,
corresponding to the number of sublenticles, in such a way that a
nearly homogeneous luminance distribution in the region of
visibility results.
[0053] For an arrangement according to the invention, a number of
accompanying images multiplied in correspondence with the number of
sublenticles occur in the preferred region of visibility after
opening the shutter. Said images are each characterized by the
appropriate accompanying trapezoid-shaped luminance distribution.
Said luminance distributions are offset from each other in an
overlapping manner. According to the invention the laterally offset
trapezoids, while overlapping, lead to a broadened resulting
luminance. The resulting luminance of an opening therefore is
clearly broadened so that the images of several openings
originating from a lenticle overlap.
[0054] In the region of visibility, the laterally adjacent openings
produce the mentioned broadened trapezoid-shaped luminance
distributions. With the arrangement according to the invention the
marginal regions thereof are overlapping.
[0055] Each of the mentioned trapezoid-shaped luminance
distributions consists of a rectangular ideal distribution of the
bundle of rays and of sloping margins, which are caused by the real
optical properties of the sublenticles arising from the "point
spread function".
[0056] Due to their inventive arrangement and alignment, said
margins of the luminance values in the region of visibility
overlap, whereby according to the idea of the invention, working
backwards from the required luminance overlappings--from each
opening and laterally adjacent openings--as well as from the
defined geometry of these openings and considering the point spread
function, the arrangement of sublenticles and in particular the
alignment of sublenticles--especially the inclination of the
optical axis of each sublenticle--are determined.
[0057] With the substantially maximum overlapping of these margins
of the images of the openings, a nearly homogeneous resulting
distribution of the luminance is created at these transition
regions. This results in a nearly homogeneous illumination in the
region of visibility and on the display.
[0058] The darker regions between the images of the openings are
almost eliminated, and the quality of the image representation is
enhanced noticeably for the viewer.
[0059] With a further division of the lenticles in terms of
approximating an aspheric lenticle the resulting luminance
distribution is substantially improved. This approximation is also
valid for an asymmetric lenticle, whereby particularly in this case
the arrangement and inclination of the sublenticles can differ.
Simpler embodiments of the multi-lens lenticular array have
symmetries such as equal angles of inclination and/or a symmetric
arrangement of the sublenticles.
[0060] Preferably, a central, large sublenticle is arranged in the
region of the central axis of the lenticle and hence in the region
of small aberrations.
[0061] The multi-lens lenticular array according to the invention
is also advantageous in known designs of double lenticular arrays
with vertices in the same or in opposite directions and is also
usable in crossed lenticular arrays. The integration of a field
lens into a multi-lens lenticular array is also conceivable.
[0062] An autostereoscopic display with one or more multi-lens
lenticular arrays according to the invention is characterized by
its usability in 2D- and/or 3D-mode, its multi-user suitability,
its enablement of free mobility of the viewer, its high resolution,
its great brightness and its small depth. Thanks to its high
quality features as regards image representation and low
cross-talk, it is well suited for high-end applications in the
fields of medicine, technology, research and development, for
mid-range applications in video-conference systems and
administration, in financial institutions, and in insurance
companies, and for low-end applications, e.g. home displays,
videophones and many other applications.
SHORT DESCRIPTION OF FIGURES
[0063] The following figures illustrate examples of embodiments of
the multi-lens lenticular array according to this invention, and an
illumination device according to the invention, as components of an
autostereoscopic display.
[0064] The figures relate to a lenticle of the multi-lens
lenticular array and what is shown is:
[0065] FIG. 1a to 1c a multi-lens lenticular array of this
invention which is divided into three sublenticles with parallel
optical axes;
[0066] FIG. 2 a multi-lens lenticular array of this invention is
divided into three sublenticles, whereby the optical axes of the
sublenticles arranged at the margins are inclined towards the
central axis;
[0067] FIG. 3 a schematic view of transitions between neighboring
sublenticles;
[0068] FIG. 4a a schematic view of the arrangement of sublenticles
which approximate an aspheric lenticle segment;
[0069] FIG. 4b a schematic view of the arrangement of sublenticles
which approximate an aspheric and an asymmetric lenticle
segment;
[0070] FIG. 5 a schematic view of the distribution of the bundles
of rays of an illumination device for an autostereoscopic display
with a multi-lens lenticular array of this invention;
[0071] FIG. 6 a representation of the distribution of the bundles
of rays which expands on FIG. 5 in greater detail.
PREFERRED EMBODIMENTS
[0072] FIG. 1a shows a first embodiment of the multi-lens
lenticular array. Here a lenticle L is divided into three
sublenticles S1 to S3. In the center of the central axis m of the
lenticle L there is a large central sublenticle S2, and two other
smaller sublenticles S1, S3 border on it and are arranged at the
margins. The sublenticles S1 to S3 together cover the aperture of
the lenticle L. The optical axes of the sublenticles are aligned
parallel to the central axis m of the lenticle.
[0073] When compared with FIG. 1a, the embodiment of FIG. 1b shows
the same sublenticles. But the sublenticles S1 and S3 arranged at
the margin are shifted in the axial direction of the central axis
m. With the same radii of curvature R1 and R3 as in FIG. 1a, the
centers of curvature M1 and M3 each are shifted in the axial
direction of the central axis, m, i. e. in the direction of
propagation of the light.
[0074] For comparison, the sublenticles S1 and S3 in FIG. 1c are
arranged offset in opposite directions. FIG. 2 shows a lenticle
divided similarly to FIG. 1. The sublenticles S1 and S3 arranged at
the margins, however, have an optical axis inclined relative to the
central axis m. Such an embodiment is preferred as the inclined
sublenticles S1 and S3 implicitly include an optical wedge term.
The path of rays through the margins of the lenticle can be
advantageously influenced by the inclined sublenticles.
[0075] FIG. 3 shows a schematic view of transitions between
neighboring sublenticles. A first transition shape F1 shown on the
left of FIG. 3 is coherent with the edge, whereby the sublenticles
have a line of intersection, s, in common. Another transition shape
F2 is coherent without an edge, whereby the sublenticles have a
tangential plane in common so that here a sublenticle without an
edge passes into a neighboring sublenticle. As shown in the figure,
the transition shape F3 is discontinuous, i. e. interrupted.
[0076] The transition between two neighboring lenticles is
similar.
[0077] FIG. 4a shows an embodiment of sublenticles which
approximates an aspheric lenticle. There is a central sublenticle
S2 and two sublenticles S1 and S3 offset from the central axis m
towards the edges. Here the sublenticles S1 to S3 have about the
same radius. By combining the sublenticles S1 to S3 an aspheric
lenticle is approximated.
[0078] FIG. 4b shows an embodiment of a coherent transition of
sublenticles without an edge. Here a central sublenticle S2 has an
inclined optical axis. The region shown on top of the drawing of
this sublenticle S2 passes coherently without an edge into the
smaller sublenticle S1. By combining the sublenticles S1 and S2, an
aspheric lenticle is approximated.
[0079] In the following, the multi-lens lenticular array according
to the invention is explained for an autostereoscopic display in
particular. In a first part the display in the direction of light
propagation consists of an illumination matrix 7 with a plurality
of controllable, openings illuminated in transmission.
[0080] The illumination matrix 7 here is exemplarily realized as
being non-luminous, but consists of the backlight 1 as the light
source and a shutter 2 having a plurality of openings 21 disposed
in a matrix-like arrangement for controlled illumination in
transmission.
[0081] A focusing matrix 8 follows, which consists of a lenticular
array LM with a plurality of lenticles L bordering each other which
are each aligned parallel to the columns or rows of the openings 21
of the shutter 2.
[0082] By means of the matrix 8 the light of these openings 21 is
focused such that a subsequent transmissive information panel 5 and
a selectable preferred region of visibility 6 are directly
illuminated in the viewer plane 9.
[0083] FIG. 5 shows a section of the illumination matrix with a
multi-lens lenticular array LM and a schematic representation of
the distribution of the bundles of rays for an opening 21 of the
shutter 2.
[0084] The matrix 8 according to the invention consists of a
multi-lens lenticular array, the lenticles L of which are divided
into several sublenticles S1, S2, . . . .
[0085] In this schematic embodiment, the sublenticles describe a
simple form of the discrete approximation to an aspheric lenticle
considered individually. Here a given lenticle L of the multi-lens
lenticular array LM is divided into three sublenticles S1 to S3. A
sublenticle S2 is in the center of the optical axis m of the
lenticle L. Two other sublenticles S1 and S3 are arranged
symmetrically with respect to the sublenticle S2. The sublenticles
S1 to S3 cover the aperture of the lenticle L and divide it into
three intervals of equal length. The multi-lens lenticular array LM
is planar on its light entry side. The optical axes of the
sublenticles S1 and S3 being at the margins, each is inclined
relative to the central axis m of the lenticle L.
[0086] The vertically hatched area shows exemplarily the
distribution of the bundle of rays B2 from the central opening 21
of the shutter 2 passing through the central sublenticle S2 up into
the viewer plane 9.
[0087] With the basic points of the trapezoid B-B' the accompanying
distribution of the luminance V12 in the region of visibility 6 in
the viewer plane 9 is represented. This trapezoid-shaped
distribution consists of the rectangle of the ideal distribution of
the bundle of rays as well as of blurred marginal regions. Said
marginal regions are caused by the real optical properties of the
sublenticles and can be described through the "point spread
function".
[0088] The superimposed bundles of rays B1 and B3 of the
sublenticles S1 and S3 are represented at the margins by the
diagonally hatched areas. The bundle of rays B1 runs through the
sublenticle S1 (shown on top in the drawing) and provides in the
viewer plane 9 the accompanying course of the luminance
distribution V11; the trapezoid of the luminance distribution V11
is marked with the basic points A-A'. By analogy the basic points
C-C' identify the trapezoid of the luminance V13 which results from
the bundle of rays B3 for the sublenticle S3 arranged on the bottom
of the drawing.
[0089] The superimposition of the luminances V11 to V13 results in
the luminance distribution V shown by a dashed line. Thanks to the
generated multiplication of the number of images, which according
to the invention is equal to the number of sublenticles (here
S1+S2+S3=3), and the laterally overlapping shift of the images, a
broadened homogeneous region of the resulting luminance
distribution V is created. The resulting region of the luminance V
runs with its sloping marginal regions between the basic points A
and C', and is correspondingly broadened.
[0090] Analogously to FIG. 5, FIG. 6 shows a device according to
the invention; a schematic representation is shown of the
distribution of the bundles of rays from three openings 21 of the
shutter 2 through the multi-lens lenticular array LM up to the
images of the openings 21 in the preferred region of visibility 6
of the viewer plane 9.
[0091] With respect to the preferred region of visibility, these
three openings 21 originate from the same lenticle L.
[0092] In the region of visibility 6 the images of the three
openings 21 create the courses V1 to V3 of the broadened luminances
previously explained in FIG. 1, resulting from V11 to V13
respectively. According to the invention, the division of a given
lenticle L into sublenticles and the arrangement and alignment of
the sublenticles S1, S2, . . . causes the overlapping sloping
marginal regions of the luminance V1 to V3.
[0093] The paths of the bundles of rays from the sublenticles S1 to
S2 arranged according to the invention are directed such that the
sloping marginal regions of the images V1 to V3 of the three
openings 21 superimpose. The dashed line shows the course V of the
luminance resulting from the superimposition of V1 to V3.
[0094] The resulting distribution of the luminance V is therefore
characterized by only a very small fall off in the luminance V in
the region of the superimposed marginal regions. Thus according to
the task of the invention, a nearly homogeneous resulting
distribution V of the luminance develops in the entire preferred
region of visibility 6.
[0095] With the substantially maximum superimposition of these
marginal regions of the images of the openings, a nearly
homogeneous resulting distribution of the luminance develops in
these transition regions. Thus in the region of visibility as well
as on the display a nearly homogeneous illumination results. Darker
regions between the images of the openings are substantially
eliminated and the quality of the image representation is visibly
enhanced for the viewer.
REFERENCE LIST
[0096] TABLE-US-00001 LM multi-lens lenticular array L lenticle of
the lenticular array m central axis of the aperture of the lenticle
S1, S2, . . . sublenticle of the lenticle SZ centrally arranged
sublenticle 1 backlight 2 shutter; with 21 openings 5 transmissive
information panel 6 preferred region of visibility 7 illuminating
matrix 8 focusing matrix 9 viewer plane B1 to B3 distribution of
the bundle of rays from an opening A-A' to C-C' basic points of the
trapezoid of the luminance in the viewer plane for the bundle of
rays B1 to B3 V11 to V13 distribution of the luminance through one
opening V1 to V3 distribution of the luminance through three
openings V resulting distribution of the luminance
* * * * *